I think I get the genral drift here, but in laymans terms, what the impacts of the new low point - more chance of backup? Thanks, appreciate the feedback.

: Don't connect to the bottom of an existing drain. You would be creating a new low point for your system. You must pitch down (at least 1/4" per foot) to either level or above the existing drain line. Consider a sewage ejector if it's real important for you to add this to your basement.